Monolithic Power Systems Inc. MPQ2490DS-LF-P

Overview

MPQ2490DS-LF-P from Monolithic Power Systems is an industrial-grade, current-mode synchronous step-down DC/DC converter with programmable output current limit. It delivers 1.5A continuous output over 4.5V–36V input, supports 0.8V–15V adjustable output, features fixed 700kHz switching frequency, and integrates a 0.25Ω internal high-side MOSFET. Used in automotive cigarette lighter adapters and industrial power supplies where robust overcurrent protection and DCR-based current sensing are required.

For engineers reviewing the MPQ2490DS-LF-P datasheet, MPQ2490DS-LF-P pinout, MPQ2490DS-LF-P application, or MPQ2490DS-LF-P equivalent, this page provides verified functional identity, validated QFN10 (3×3mm) package mapping, confirmed ISP/ISN current-sense architecture, thermal shutdown behavior, and real-world current-limiting implementation using either sense resistors or inductor DCR.

Technical Context

The MPQ2490DS-LF-P implements peak-current-mode control with integrated slope compensation and a dedicated load-current limiting loop that regulates via the SS pin when V_ISP–V_ISN ≥ 100mV. Its error amplifier drives both voltage regulation (FB pin) and current-limiting (SS pin) paths independently.

It uses a 700kHz oscillator with fold-back frequency reduction below 250mV FB voltage during short-circuit events, and incorporates cycle-by-cycle overcurrent protection plus thermal shutdown at 150°C. The BST-SW bootstrap circuit enables high-side gate drive without external diode in most configurations.

Key Specifications

Pinout & Package

MPQ2490DS-LF-P is housed in a thermally enhanced QFN10 (3mm × 3mm) package with exposed thermal pad soldered to PCB ground plane for optimal power dissipation (θ_JA = 50°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar programmable-current-limit buck converter applications.

Compared with MPQ2490DS-LF-P, MPQ2451DQ-LF-Z omits programmable current limiting entirely, while LM5164QPWPRQ1 achieves similar functionality only with added external components-making MPQ2490 the most integrated, cost-effective choice for industrial programmable-current buck conversion.

Availability

MPQ2490DS-LF-P is available at Aetrix Electronics and suitable for industrial power supplies, automotive accessory adapters, and battery charger front-ends requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MPQ2490DS-LF-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, motion control, and interface applications.

The MPQ2490 belongs to MPS's industrial-grade DC/DC converter product line, designed specifically for ruggedized power conversion in automotive, factory automation, and transportation systems where programmable protection and wide-input operation are critical.

FAQ

What is the exact function of the SS pin beyond soft-start?

The SS pin serves dual roles: it controls soft-start ramp rate via external capacitor, and acts as the error amplifier output for the current-limiting loop. When V_ISP–V_ISN exceeds 100mV, the current-limit amplifier pulls SS low to reduce duty cycle and clamp output current-making SS central to both startup sequencing and real-time overcurrent regulation.

Can the MPQ2490DS-LF-P operate without an external bootstrap capacitor?

No. The BST pin requires a 0.1μF ceramic capacitor connected between BST and SW to generate the floating gate-drive voltage for the internal high-side MOSFET. Omitting this capacitor prevents proper high-side switching, causing immediate failure to regulate and potential damage due to shoot-through or excessive V_GS stress.

How does the MPQ2490 handle short-circuit conditions?

During output short, FB drops below 250mV, triggering oscillator frequency fold-back from 700kHz to 200kHz to reduce power dissipation. Simultaneously, the current-limit loop pulls SS low, forcing duty cycle reduction. If average current exceeds 120% of programmed limit, a fast comparator shuts off the switch entirely until recovery.

Is the EN pin internally pulled up or does it require external bias?

The EN pin has no internal pull-up or pull-down. It must be driven actively high (≥2V) to enable operation or actively low (≤0.4V) to enter shutdown mode drawing only 4μA. Leaving EN floating results in undefined operation and possible erratic startup or latch-up behavior.

What is the maximum recommended inductor DCR for accurate current sensing?

For DCR-based current sensing, the inductor's DCR should be ≤100mΩ to ensure sufficient signal-to-noise ratio at the ISP/ISN inputs. Higher DCR increases sensitivity to temperature drift and copper resistance variation, degrading current-limit accuracy-especially across –40°C to +125°C operating range.

Does the PGOOD pin indicate both undervoltage and overvoltage faults?

No. PGOOD monitors only the FB voltage relative to the 0.8V internal reference. It asserts low only when FB falls below 90% of 0.8V (i.e., <0.72V), indicating output undervoltage. It does not respond to overvoltage conditions; external supervision circuitry is required for OVP protection.

What is the minimum output capacitance required for stability?

The MPQ2490 is stable with ≥10μF total ceramic output capacitance (X5R/X7R). Lower values risk phase-margin degradation and oscillation, especially under light-load conditions. Layout parasitics and ESR must also be minimized-keep capacitor leads short and place directly at FB/GND nodes.